Circuit breaker



sept 24, 1940- o. s. JENNINGs 2,215,792

CIRCUIT BREAKAER s sheets-smelt 1 Filed sept. 1o, 1937 lNyENToR Olive/"SJennings.

BY zum 'A ATToRN WITNESSES:

`jJm

O. S; JENNINGS cIRcUT BREAKER Filed sept. 10, 1937 3 Sheets-Sheet 2INVNTOR Oliver 5T .fen/227295. x BM d ATToR Y Sept. 24, 1940.

WITNESSES:

Patented sept. 24, 1940 UNITED STATES CIRCUIT BREAKER Oliver S.Jennings, Pittsburgh, Pa., assignor to Westinghouse Electric &Manufacturing Company, East Pittsburgh, Pa., a. corporation ofPennsylvania Application September 10, 1937, SerialNo. 163,212

Claims.

The invention relates in general to circuit breakers and is particularlyconcerned with circuit breakers of the type used for controllinglighting and moderate power distribution feeder 5 circuits.

An objectv of the invention is the provision of an improved circuitbreaker which is operable to automatically open the `circuit in responseto an overload or abnormal condition and which will automaticallyreclose itself when, and only when, the condition causing the overloadis removed or cleared from the controlled circuit.

Another object of the invention is theI provision of a circuit breakerof the type mentioned which is simple and inexpensive to manufacture andwhich is .safe and reliable in operation.

Another object of the invention is the provision of a circuit breaker ofthe above-mentioned type that is both manually operable andautomatically operable to open and reclose the circuit.

. The novel features that are considered characteristic of the inventionare set forth in particular in the appended claims. The invention itselfboth as to structure and operation, together with l additional objectsand advantages thereof, will best be understood from the followingdescription of several embodiments thereof when read in connection withthe accompanying drawings, in which:

Figure 1 is a vertical sectional view o f an automatic circuit breakerembodying the features of the invention, the various parts being shownin the positions they occupy when the breaker is closed; 35 Fig. 2 is avertical sectional view of the circuit breaker, similar to Fig. 1,showing the parts in tripped open position following the occurrence ofan overload of predetermined magnitude and duration;

Fig. 3 is a vertical sectional view of the circuit breaker, similar toFig. 2, showing the position of the parts in the tripped open positionfollowing the occurrence of an overload, the latch means being shown inthe operative position in which it prevents reclosing of the breaker;

Fig. 4 isa horizontal sectional view'of the circuit breaker shown inFig. 1, taken on the line IV-IV of Fig. yl;

Fig. 5 is a schematic diagram illustrating the circuit which itcontrols;

Fig. 6 is a vertical sectional view of a modified form'of automaticcircuit'breaker which includes means 'for manually opening and closingthe contacts of the breaker;

electrical connection of the circuit breaker in the (Cl. F75- 294) Fig.7 is a horizontal sectional view of the circuit breaker shown in Fig. 6,taken on the line VII- VU of Fig. 6, the electromagnetic latch meansbeing omitted in order to simplify the -fgure; and

Fig. 8 is a schematic diagram illustrating a In the present invention,however, there is provided .in cooperative association with the breakera novel means for preventing reclosing of the contacts of the breakerduring the existence of the .condition causing the overload.

Referring to Figs. 1 through 5, inclusive, the single-pole double-breakcircuit breaker illustrated comprises in general a recessed base 9, apair ofA spaced stationary contacts I'I, a. pair of cooperating movablecontacts I3, an actuating mechanism indicated generally at I5 which isoperable in response to predetermined overload conditions to move thecontacts I3 to open circuit position, and which is automaticallyoperable after a predetermined time to return the movable contacts I3 toclosed circuit position, and a means indicated generally at I1 forpreventing reclosing of the contacts during the existence of thecondition causing the overload.

The various parts of the circuit breaker are supported and enclosed bythe base 9, which is of molded insulating material, and if desired, acover I9, also of'molded insulating material, may be provided forclosing the open side ofthe base.

Two strips of conducting material 2| aresupported on the base 9 by meansof screws 23. -A portion of each of these strips extends through theupstanding end wall of the base 9 in order to provide terminals for thebreaker, suitable screws 25 being provided for connecting the line andload conductors thereto. The stationary contacts II are aiiixed to theinner ends of each of these conducting strips 2ly by means of the screws23.

The two movable contacts I3 are c arried by a switch member consistingof a pair of U-Shaped bimetallic control elements 21. Each of the bimetallic control elements 21 comprises a substantially ilat strip ofbimetallic material which- -ments 21. The ends of the control ,elementsopposite tothe ends whereon the contacts lI3 are supported areelectrically and mechanically connected by means of a tie member 3 Iwhich comprises a fiat strip of conducting material riveted to the endsofthe elements 21. A The interconnected control elements 21 arepivotally supported upon two spaced upstanding members 33 of insulatingmaterial, each of which is provided with a suitable bearing portion forengaging one of the pivot pins 29 of the control elements 21. Thesupport members 33 are secured to the base by means of suitable screws3l.

The bimetallic control elements 21 constitute a part of the actuatingmeans of the circuit breaker which will now be described. 4In additionto the bimetallic control elements 21, the actuating means of thebreaker includes a U-shaped pivot actuating member 31 and a pair ofovercenter springs 39 which connect the free end of the actuating member31 to the tie member- 3I"of the bimetallic control elements. Theactuating member'31 is substantially U-shaped and ispivotally supportedon a U-shaped support 4I secured to the base by means of screws 43. Thepivot ends of the actuating member 31 are provided with bearing portions45 (Fig. 4) for envsprings 39.'

gaging the pivot pins 41 carried by the support 4I. The tie member 3iand the cross portion 49 of the actuating member 31 are provided withopenings which are engaged by the'bent ends of the overcenter springs39.

A bracket member 5I, which is fastened to the base 9 by suitable means,is provided for defining the limits of motion of the actuatingmember31,' these limits being adjustable by means of set screws 53 and 55. Thelimit of motion of the switch member consisting of the control elements21 in a counter-clockwise direction about their pivot pins 29 is definedby the engagement'of the moving contacts I3 with the stationary contactsII, and the movement of the switch member in a clockwise direction isdened bythe engagement of the upper side of the contact end of each ofthe bimetallic elements 21 with a projection 51 that extends inwardlyfrom the end wall `of the base 9.

through the tie member 3|, which connects the ends of the looped controlelements, through the other looped control e1ement.21`v and itsassociated movable contact I3 to the opposite stationary contact Il andthence through the second conductingstrip 2l to the load.

It will be noted, as shown particularly in Fig. 4, that the spacebetween the two bimetallic control elements 21 is entirely clear inorderto permit free motion of the overcenter operating Th circuitbreaker. thus fardescribed is substantially the same as the automaticcircuit breaker disclosed in the aforementioned Patent No. 2,070,305.'Ihe operation of --the breaker as n thus' far described is briefly asfollows: When thebreaker is in closed position, as shown in Fig.

1, and. an overload of suillcient magnitude and duration occurs in thecircuit controlled by the.

breaker, the bimetallic -control elements ,21 are heated suillciently tomove the tie member 3| in an upward direction away from thestationarycontacts II. So long as thismovement does not bring the line of actionof the overcenter springs 39 above the pivot axis 41 of the actuatingmember 3'1, the breaker will remain in closed circuit position. If,however, the overload is of suillcient magnitude and duration to causethe tie member to be moved a sumcient amount to change the line ofaction of the springs 39 relative to the pivot axis 41, it is apparentthat the circuit breaker is in an unstable mposition due to the fact4that the overcenter moves the line of action of the overcenter springsv39 above the pivot axis 29 of the switch member consisting of thecontrol elements 21, thereby producing a component of force tending tomove -these elements in a clockwise direction about their pivot. Thisresults in the movement of the control elements 21 and the movablecontacts carried thereby from the closed' position shown in Fig. 1 tothe open position shown in Fig. 2 with a snap action.

In the absence of the means for preventing reclosing of the breaker, theactuating means automatically recloses the contacts in the followingmanner. 21 have cooled, these elements assume their normal conditionshown in Fig. l causing the tie member 3| to be moved downwardly. Thedownward movement of the tie member 3l -moves the line of action ofovercenter springs 39 below the pivot axis 29 to eiect movement of thecontrol elements 21 and movable contacts I3 from openy Afterthe-bimetallic control elements` to closed position with a snap action.The movement of the control elements 21 to closed position moves theline of action of the overcenter springs 39 below the pivot axis 41 ofthe actuating member, so that the springs effect clockwise movementofthe actuating member 31 from the position shown in Fig. 2 vback to theposition shown in Fig. 1.`

In the above description of the operation of the breaker, it has beenassumed that the move. ment of the bimetallic control Aelements 21occurred in-response to internal heating produced by the flowtherethrough of an overload current.

It is quite possible, however, to cause automatic operation of thebreaker to take place as a result of changes in the temperature ofthemedium surrounding the breaker. Thus if the circuit breaker isdisposed .within a transformer tank in such a manner that the bimetalliccontrol elements are in contact with the oil used for insulating thetransformer, 'the operation of the circuit breaker might result from asteady increase in the temperature of theoil. If the operation of thecircuit breaker is affected by the heating ofthe surrounding medium, thebreaker will in most instances'I remain in open .position for aconsiderable Vperiod of time due to the fact that the cooling of thelarge body of oil within the transformer tank takes place comparativelyslowly.

Referring now to the means indicated generally at I1 for preventingreclosing of the circuit breaker during the existence of the conditioncausing the overload. This means comprises in.

general a pivoted latch 59 of magnetic-material or at least having aportion of magnetic material to form an armature, an electromagnet 6|for moving the latch from released position to latching position whenenergized a predetermined amount, and a transformer 63 for energizingthe electromagnet 6|. The latch 59 is pivotally supported by means of apivot pin 65 projecting from the side wall of the base 9 and is biasedto an inoperative released position by means of a coiled compressionspring 61 a portion of which extends within a bore provided -in the coreof the electromagnet 6| One end of the spring engages a projectionprovided on the latch 59, while the other endof the spring engages anadjusting screw-69 which serves as an adjusting means for adjusting theamount of current required to move the latch from released to latchingposition.

The electromagnet 6| comprises a core 1| and a winding 13. Theelectromagnet is supported by an angle bracket 15 of magnetic materialwhich is secured to one of the side walls of the base 9. The horizontalportion11 of the bracket 15 serves to support a pair of spaced contacts19 and 8|, which are insulated from the bracket 15 by means ofinsulating spacer plates 83. vThe contacts 19 and 9| are adapted to bebridged to complete a circuit for the winding 13 of the electromagnet 6|when the breaker is in open position, by means o'f a bridging plate 85of ,conducting material which is secured to the tie member 3| andinsulated therefrom by means of an insulating plate 81, the bridgingplate being disposed between the ends of the springs 39, as best shownin Fig. 4.

The transformer 63 is mounted on the ba'se 9 on any suitable location,and comprises a core 89, a primary winding 9| and a secondary winding 93(Fig. 5). The internal electrical connections of the electromagnet 6|,the contact means 19, 3|, 85 and the transformer 63 are illustrated inthe schematic diagram shown in Fig. 5. 'Ihe primary winding 9| of thetransformer 63 `is connected in shunt relation across the contacts ofthe breaker by means of conductors 95 and 91, one terminal of thewinding 9|. being connected by the conductor 95 to the line conductorstrip 2|, and the other terminal of the primary winding being connectedby conductor 91 tothe load conductor strip 2|. One terminal of thesecondary winding 93 of the transformer 63 is connected to one-end ofthe winding of the electrovmagnet 6| by means of a conductor 99, theopposite terminal of the winding' 93 being connected to the return wireIDI by means .of .a conductor |93. 'I'he opposite end of the winding 13of the electromagnet 6| is electrically connected to the contact 8| bymeans of a conductor |05, while the other contact 19 carried by thebracket 15 is connected to the load conductor strip 2| by means of aconductor |01. It will thus be seen that -the primary winding 9| of thetransformer 63 is shunted by the contact means of the breaker when thebreaker is in closed circuit position, so that lthe transformer issubstantially deenergized under these conditions. A.It will also be seenthat the electromagnet 6|is adapted to ber automatically connected byvmeans of the contacts 19, 6|, 65 in series circuit with; the sec-'ondary 93 of thev transformer 63 and directly across the load and inseries therewith when the breaker is in open circuit position.

Theoperation of the means for preventing reclosing of the contacts ofthe breaker is brieiiy circuit" position.

as follows: .With the circuit breaker in closed position, as shown inFig. 1, the transformer 63 is shunted by the breaker contacts, so thatit is substantially deenergized and nol current ows through theelectromagnet 6|. Thusthelatch 59 is maintained by the spring 81 ininoperative or released position. lWhen an overload in the circuitcontrolled by the breaker occurs, the switch member and movable contactsI3 are automatically moved to the open circuit position inthe mannerpreviously described as a result of the flexing o'f the bimetalliccontrol elements 21. When the movable contacts i3 separate from thestationary contacts and the arc is extinguished, current iiows throughthe primary of the transformer 63 since it is no longer shunted bythecontact means of 4the breaker. This materially reduces the flow ofcurrent to the load so as to protect the circuit and load apparatus.When the switch member and movable contacts I 3 have reached their fullopen circuit position, the bridging plate 85 bridges the stationarycontacts 19 and 8| to complete a circuit for the electromagnet 5| whichconnects the electromagnet 6| in series circuit with thesecondary-Winding 93 of the transformer B3 and the load. Since thetransformer 63 is energized due to the opening of the main contacts ofthe breaker, the electromagnet`6| is now energized an amount dependingupon the impedance of the load since it is in series therewith. If theimpedance of the load is below a predetermined amount, that is to say,

if the condition causing the overload still exists,

the electromagnet 6i is energized a sufficientamount by the currentflowing through its winding to move the latch from its inoperative orreleased position, as shown in Fig. 2, to latched position, as shown inFig.3, in which it engages the tie member 3| connecting the bimetalliccon-v trol elements 21 to hold `these elements in open Under theseconditions, the switch member and the movable contacts I3 are heldlatched in open position to prevent reclosing ofv the circuit breaker.The circuit breakerA cannot be reclosedby the actua-ting mechanism untilthe impedance of the load is increased as by reducing the magnitude vofthe load to a value substantially equal to or less than a safe normalfull load value, or until the fault condition causing the overload iscorrected or cleared. V When this is done, the pull of the electromagnet6| is reduced because of the reduction in the current flowing throughits winding so that .the force exerted by the biasing spring 61 issumcient 'to move the latch to its inoperative or released position, asshown in Fig. 2 to release the switch member. I'he actuating mechanismis .now free to automatically reclose the circuit breaker.

When the latch 59 releases the tie member- 3|, the bimetallic controlelements 21 which have cooled a sufficient amount, move the line ofaction of the overcenter springs 39 below the pivoted axis 29 ofthevcontrol elements 21 to eil'ect automatic reclosing of the circuitbreaker vin the v manner previously described. y

|The adjusting screw 69 .forms a simple adjusting means: for adjustingthe amount of current required to cause the electromagnet to move thelatch from inoperative to latching positiomso that the lock-out means |1may be adjusted to operate under different predetermined circuitconditions.

The magnetic circuit of the electromagnet 6| is so designed that thelatch I9 'will be moved to its in any number of ways, one way being tohave a very small air gap between the armature portion of the'latch 59and the core 1I of the' electromagnet.'

vA modification-of the invention is illustrated in' Figs. 6 and 7. Thestructure of the circuit breaker in this modiiication is substantiallysimilar to the previously described circuit breaker and to theembodiment shown and described in connection with-Figs. 8 and 11 'of theaforementioned Patent No. 2,070,305. In this modification, the circuitbreaker 'is provided with a manual operating means for opening andclosing the breaker. Since the basic structure is substantially similarto the device previously described, the same reference characters willbe lused wherever applicable.

The circuit breaker illustrated in Figs. 6 and '1 comprises in general arecessed base 9 of molded insulating material, a pair of stationarycontacts II, a pair of cooperating movable contacts I3, an

actuating means indicated generally at I5, al

means indicated generally at I1 for preventing reclosing of thecircuitbreaker during the existence of the condition causing anoverload, and a manual operating means indicatedgenerally at Thestationary contacts I I are secured to a pair of terminal conductingstrips 2| which are .in turn secured to the base 9 by means of screws23.

'I'he movable contacts I3 are carried by a switch member consisting oi apair of U-shaped bimetallic control elements 21, the upper ends of whichare mechanically and electrically connected together by means of a tiemember 3| of conducting material. The control elements 21 are providedwith pivot pins 29 for) pivotally mounting the elements on a pair ofspaced supporting members`33 of insulating material.

The bimetallic control elements 21 form a part of the actuating meanswhich will now be brieily described. The actuati'ng'means for thebreaker includes the bimetallic control elements 21, a U- shapedactuating member 31 pivoted at 41 on a support 4|, al pair of overcentersprings 39 connecting the free end portion 490i the actuating member 31to the tie member 3|.`

The movement of the switclimember consistl ing of the bimetallic controlelements 21 and the movable contacts I3 in a clockwise direction abouttheir pivot axis is limited by an inwardly extending projection'51formed on the end wall of the base 9.

A bracket member 5| is provided for deiining the limits of movementofthe actuating member 31,'these'limits being adjustable by means of setscrews 53 and 55.

The means I1 for preventing reclosure of the circuit breakery isidentical to the correspondingV means of the previously describeddevice, andV comprises generally a pivoted magnetic latch 59 l biased toreleased or inoperative position by a spring 81, an electromagnet`6| formoving the latch from released to latching position when energized apredetermined amount, and a transformer indicated generally at 63 forenergizing the electromagnet 6I. The electromagnet 9| is provided withan adjusting screw 69 which serves asan adjusting means for determiningtire amount of vcurrent required to move the latch from inoperative tolatched'position.Y A pair of stationary contacts 19 and gl are'supported by and closing the contacts of the breaker.

Vthe bracket which supports the electromagnet 6| and insulated therefromby the insulating plates 93. These contacts 19 and 3| are adapted to bebridged by a bridging plate 85 of conducting material which is securedto the tie member 3| and insulated therefrom by an insulating platelA91.

' the contact means of the breaker.

In this modication of the invention, the circuit breaker is providedwith a manual means indicated generally at |09 for manually opening Themanual means |09 comprises in general a bifurcated operating member IIIwhich straddles the actuating mechanism and which is pivotallyvsupported by means'of pivot pins ||3 on the support 4|, an operatinghandle II5 secured to the bight portion of the operating member III andapair of depending projections ||1 and IIB formed integral with the bightportion of the operating member III. The handle ||5 projects through anopening I2 I provided therefor in the cover |23 of the base, and has-aclosure portion which acts to close the opening in any position of thehandle. Y

The actuating member 31 of the actuating means of the circuit breaker isprovided with a Y- shaped coupling member |21, the legs of which aresecured to the legs of the actuating member 31 by means of rivets |29(Fig. '1). The upper end |3I of the VY-shaped coupling member |21 isdisposed between the depending projections II1 and II8 'of the operatingmember III for engagement thereby when the operating handle II-5 ismoved.

The ,spacing of the projections ||1 and IIB is such that they-permit theactuating member 31 to be movedY independently of the operating handleduring automatic operation of the actuating means when the handle is inclosed circuitv ber III of insulating material which extends 'I Athrougha slotted opening |43 in one of the side walls of the base 9. Thismember Ill permits the latching member |33 to be moved so as todisengagethe operating handle and permit manual operation of thebreaker.A The latch |33 is biased by a spring I (Fig.y '7) towardslatching position so as to latch the operating member II I when the sameis moved to clo'sedcircult -V position.

The circuit breaker is -shown in the closed circuit position in Fig. 6.It will be noted that the latch |33 through engagement of the latchrecess '.I31 with the pin .|39 holds the operating'member II in closedcircuit position. If it is desired to manually open the breaker, Vthelatch |33 is lifted by means of the insulating projection III and thehandle is moved in a counter-clockwise direction. During this movement,the projection |3| vof the coupling member |21 then disengages theprojection H1 and moves with the actuating member 31 towhich it issecured, under the biasing vaction of the overcenter springs 39 to opencircuit position. In moving to this position, the

line of action of the overcenter springs 39 is carried across and .abovethe pivot axis 29 of the bimetallic control elements 21, and thesemembers together with the movable contacts carried thereby move to opencircuit position with a snap action. s

In manually` closing the circuit breaker, substantially the reverseaction takes place. TheA operating handle H5 is moved in a clockwisedirection about its pivot H3 to close the contacts of the breaker.During this movement, the depending projection H8 engages the upper end|3| of the coupling member and moves that member together with theactuating member 31 to which it is secured in a clockwise directionabout the pivot axis 41 to the closed circuit position shown in Fig. 6.During this movement, the upper end of the coupling member |21-disengages the projection H8, and the line of action of the overcentersprings irst crosses the pivot axis 29 of the bimetallic controlelements to eiect movement of the control elements: 21 and the movablecontacts I3 to closed circuit position with a snap action, and thencrosses the pivot axis 41 Aof the actuating .member 31 to effectmovement .of that member to closedposition shown in Fig. 6.

Both the opening and the closing operations once initiated by theoperating handle take place substantially instantaneously and withincreasing acceleration as soon as the line of action of theovercentersprings 39 crosseseither of the pivot axes 29 or 41. A

As has previously been pointed out, the spacing ofthe projections ||1and ||8 is such as to permit automatic operation' of the actuating meansI5` when the handle is held latched in closed position.

The automatic operation ofv the actuating means is identical to theautomatic operation of' the device shown in'Figs. 1 to 4 and previouslydescribed in connection therewith. Briey,' when the breaker is in closedposition, the handle being held latched inclosed position, as shown inFig. 6, and a predeterminedv overload or increase in temperature of theambient medium occurs, the bimetallic control elements 21 expand in sucha manner thatthe tie member 3| is moved Vupwardly. A This upwardmovement of the tie member carries the line of action of the springs 39above the pivot laxis 41 of the actuating member 31, and the springswill exert a component biasing that member in a counter-clockwisedirection. The immediate result is to .cause the actuating member 31 tomove in a counter-clockwise direction, the limit of motion being deilnedby the engagement of the upper end |3| of the coupling member ,|21 withthe depending projection H8 of the operating member IH. As the actuatingmember 31 moves'in a counter-clockwise direction, as described above,the line ot action of the springs 39 iscarried vacross and above thepivot axis 29 ofthe connected bimetallic control elements, therebycausing those elements and the movable contacts I3 carried thereby to bemoved from closed to open circuit position with a snap action.

In the absence of the lock-out means I1, the actuating means eiectsautomatic reclosure of the contacts in the following manner: Asvthebimetallic control elements 21 cool following automatic opening of thecontacts, the tie member 3| and with it the line of action of theovercenter springs 39 is moved downwardly. As soon as the line of actionof the springs crosses the lpivot axis 29 ofthe connected controlelements,`

these elements and the movable contacts I3 carried thereby are moved toclosed circuit position with a snap action. As f this movementprosprings 39 also crosses the pivot axis 41 of the actuating member 31to cause clockwise movement of that member to the position shown in Fig.6.

The depending projections H1 and H8, which provide opposed surfaces forengaging the coupling member |21, comprise in effect alost-motionconnection between the operating handle and the actuating means. Thus,even though the handle is held in closed circuit position, as shown inFig. 6, either manually or through the agency of the latch |33, thebreaker will open4 automatically upon the occurrence of an overload.'Ihe breaker is thus entirely trip-free of the operating handle.

'I'he latch controlling electromagnet 6I and the transformer 63 areelectrically connected in the i same manner asin the embodiment shown inFigs. :1 through 5 and described in connection therewith. Theprimary ofthev transformer 63 is connected in shunt relation to the main contactsof the breaker, and the secondary winding of the transformer yisconnected lin series circuit With the electromagnet 6| and the load whenthe breaker is in open-'circuit position by means `of the contacts 19,8|, 85, as previously described in connection with Fig. 5.v

' The operation of the lock-out means indicated generally at I1 issubstantially'identical with the corresponding means described inconnection with Figs. 1 through 5. The transformer 93 becomes energizedwhen'the breaker opens, ,and the electromagnet 6| visconnected-in seriescircuit with the secondary of the transformer and with the load by the'closing of the contact means 19, 8|, 85 `when the breaker reachesfull-open circuitl position. Ifthe impedance of the load is -below apredetermined fvaluefthe current ow through the electromagnet issufcient to move the latch 59 fromlnoperative to latched position, inwhich last position it latches the switch member consisting of thebimetallic control elements .21 and the movable contacts. I3 in opencircuit position, so that the breaker cannot be reclosed until the faultcondition is cleared-or the im pedance ofthe load is increased, as, forexam-- ple, by removal of part of the load apparatus from' the circuit,When the impedance of the load ycircuit is increased above thepredetermined g5 value, or the fault condition is cleared, the pull ofthe electromagnet 9| becomes insuflicient to hold the latch 59 in itslatching'position, and the spring 61 moves thelatch to its inoperativeposition, as 'shown in Fig. v6, to effect release of the 70 switchmember. yFollowingrelease Vof the switch member, the actuatingmeansautomatlcally recloses the circuit breaker in a manner previouslydescribed.

s In order that the transformer 93 will not be u gresses, the lin e ofaction of the overcenter f 6 energized when the breaker is manuallyopened by means of the operating handle H5, a cut-out switch indicatedgenerally at |41 is provided which opens the circuit to the primary ofthe transformer when the operating handle is moved to open position toopen the breaker. The plunger |49 of the cut-out switch is moveddownwardly to open the` switch by a projection ISI formed at the lowerend oi' one of the legs of the operating member This projection IIImoves the plunger |49 downwardly to open the switch |41 when theoperating handle IIS is moved to open position. The contact means of thecut-out switch |41 are adapted to be'connected in the conductor leadingto the primary 9| of the transformer, as indicatedby the alternativedotted lines |53 in Fig. 5.

A further modification of the invention vis illus-V trated schematicallyin Fig. 8. In this modiilcation, the circuit breaker' and ltsactuatingmeans are identical' to that shown and described in connection withFigs. 1 through 4. The breaker operates automatically in the same manneras.

impedance |6| is connected in shunt circuit relationship to the contactmeans of the breaker and a resistance |93 is connected in series circuitwith the latch controlling electromagnet 6|. It will be noted that whenthe circuit breaker is in open circuit position, the contacts 19, 85,which mayA take'the form of the contact means 19, 8|, 85

shown in Figs. 1 through 4, connect the electromagnet 6| in parallelwith the load |65, the circuit for the electromagnet and the loadcircuit being connected in series with the impedance IBI.-

The operation of this modiilcation of the invention is brieily asfollows: When the circuit breaker is'opened in response to predeterminedoverload conditions, the electromagnet is connected in parallel with theload by means of the contacts 19, 85. If the impedance` of the load isbelow a predetermined value, insumcient current will flow through theelectromagnet 6| to move the latch to inoperative position, and themovable 'contacts will be held in open circuit lposition by means of thelatch 59, so that the breaker is prevented from. being automaticallyreclosed. When the impedance of the load circuit is increased above thepredetermined value, as by removing a part 'of the load from the circuitor by correcting the fault condition causing the overload, suicientVcurrent will ilow through the electromagnet 6| to move the latch 59 toits inoperative or released position. The actuating means of the circuitbreaker is now free to reclose the contacts of the breaker in the mannerpreviously described in connection with the embodiment shown in Figs. 1through 4.

It will thus be seen that the invention provides an improvedautomatically reclosing circuit breaker embodying a lnovel means forpreventing reclosing of the contacts of 'thebreaker during theexistenc'eof the condition causing the overload, the means for preventingreclosing of the contacts being automatically rendered inoperative toprevent reclosure when the fault condition is cleared.

While the invention has been disclosed in accordance with the provisionsof the statutes, it

is to be understood that various changs in the structural Adetailsthereof may be made without departing fromv the spirit of the invention.It is desired, therefore, that the-appended claims be -given thebroadest reasonable construction permissible in the light of the priorart.

Iclaimasmy invention: f, l.. In a circuit breaker for controlling a loadcircuit, relatively movable contacts, actuating means including anovercenter spring for opening and closing said contacts and anelectro-responsive element operable in response to predeterminedoverload conditionsfto cause' said spring to automaticallyv open saidLcontacts and operable to cause said spring vto automatically reclosesaid lcontacts following automatic opening thereof,

means operable upon automatic openingof said contacts for preventingreclosing of said contacts during the existence of the condition causingthe overload, said means comprising a latch normally biased to releasedposition and movable to a latchlng position to hold said contacts open,

an electromagnet for moving said latch to latching position when-energized a predetermined amount, transformer the primary of which isconnected in shunt relation tosaid contacts and -the secondary `of.whichis conriected in series with said electromagnet, and meansforfautomatlcally connecting said transformer secondary and saidelectromagnet in shunt relationto the load when said contacts areautomatically opened, the magnetic circuit of said electromagnet beingsuch that its reluctance is changed only a rela- )tively small `amountby the movement .of said Y latch to latching positioh so as to permitvreturn of said latch to released position when the currentilowingthrough said electromagnet is decreased to a value only 'slightly belowthe value required to cause said latch to be moved to latching position.A

2. In a circuit interrupter for controlling a load circuit, relativelymovable contacts, an overcenter spring for opening and closing saidcontacts, an electro-responsive control element voperable in response topredetermined conditions to cause said spring to automatically open saidcontacts and for causing said spring to automatically reclose saidcontacts after ,an interval of time following said automatic openingoperation, means operable upon automatic opening of said contacts forpreventing reclosing of said contacts until the predetermined conditionshaveceased l to exist, said means comprising a latch operable to latchsaid contacts open, and an electromagnet acting directly on said latchfor controlling the latch, means electrically connecting saidelectromagnet in shunt relation to the load circuit when said contactsare automatically opened, and an impedance connected in shunt relationto said contacts, said electromagnet causing said latch to release saidcontacts for closing immediately upon cessation of said predeterminedconditions. 4

3. In a circuit interrupter for controlling a load circuit, relatively`movable contacts, an overcenter spring forlopening and closing saidcontacts, an electro-responsive control element operable inresponse topredetermined conditions to cause said 8911113 to automatically opensaid contacts and for causing said spring to automatically re- I closesaid contacts after aninterval of time ioling its secondary connected incircuit'l with the lowing said automatic opening operation, meansoperable upon automatic opening of said contacts for preventingreclosing of said contacts during the existence of said predeterminedconditions, said meanscomprising a latch yoperable to latch saidcontacts open, an electromagnet acting directly on said latchfor'controlling said latch, means for automatically electricallyconnecting said electromagnet in shunt with the load upon automaticopening of said contacts, and an impedance connected in circuit with theload upon automatic opening of said contacts, said electrovat magnetcausing said latch to free said contacts for closing immediately uponcessation of said predetermined conditions.

4.7In a circuit breaker for controlling a load circuit, relativelymovable contacts, actuating means including an overcenter spring foropening and closing said contacts and an electro-responsive controlelement operable in response to predetermined overload conditions to'cause said spring to automatically open said contacts and for causingsaid spring to automatically reclose lsaid contacts after a timeinterval following said automatic opening operation, means operable uponautomatic opening of said contacts for preventing reclosing of saidcontacts if the impedof the conditions causing the overload.

5. In a circuit breaker for controlling a load circuit, relativelymovable contacts, actuating means including an overcenter spring foropening and closing said contacts and an electro-responsive controlelement operable in responsetofpredetermined overload conditions tocause said .spring to automatically open said contacts and for causingsaid spring to automatically reclose said contacts after a. timeinterval following said automatic opening operation, means operable uponautomatic opening of said contacts for preventing reclosing of saidcontacts if the impedance ofthe load circuit is below a predeterminedvalue, -said means comprising a latch operable tolatch said contactsopen, an electromagnet for controlling said latch,'and a transformer thesecondary of which is connected in circuit with said electromagnet andtogether with the electromag' net in shunt to the load upon automaticopening of saidcontacts, the primary'of said transformer being connectedin'shunt to the contacts.

'6. In a circuit interrupter for controlling a load circuit, relativelymovable contacts, an overcenter spring for opening and closingr lSaid.contacts.- an electro-responsive control element'operable in response topredetermined conditions to cause said lspring to automatically opensaid con- Y tacts and for causing said spring to automatically exist,said means comprising a latch operable reclose ,said contacts after aninterval of time following said automatic opening operation.'

means operable upon 'automatic opening of said contacts'for preventingreclosingof said contacts.

until the predetermined conditions have ceased to to latch said contactsopen, and an electromagnet for controlling the latch, and a transformerhavelectromagnet and its primary connected in shunt relation to saidcontacts, the'secondary of the transformer and the connectedelectromagnet being connected in shunt to the load upon auto- 5 maticopening of said contacts.

7. In a: circuit breaker forcontrolling a load circuit, relativelymovable contacts, actuating means including an overcenter spring foropening and closing said contacts, and an electro- 10 responsive controlelement operable in response to predetermined overloadl conditions tocause said spring to automatically open said contacts, and -for4 causingsaid spring. to automatically reclose said contacts after an interval oftime fol- 15 lowing said automatic opening operation, means operableupon automatic opening of said contacts for preventing reclosing of saidcontacts during the existence of the condition vcausing thegoverload,said means comprising a latch operable to 20 latch said contacts open,an electromagnet acting directly on said latch for controlling saidlatch, means for automatically connecting said electromagnet inshunt`re1ation to the load when the contacts are automatically opened,andan 26 impedance connected in shunt relation to said contacts, saidelectromagnet being operable to cause said latch to release saidcontacts for reclosing immediately upon cessation of the conditioncausing said overload.

` 8. In a circuit breaker for controlling a load circuit, relativelymovable contacts, actuating means including an overcenter spring foropening and closing said contacts and an electro-responsive elementoperable in response to predeter- 3/5, mined overload conditions tocause said spring to l' automatically open said contacts and operable tocause said spring to automatically reclose said contacts followingautomatic opening thereof, meansV operable upon automatic opening ofsaid 40 contacts for preventing reclosing ofsaid contacts during theexistence of the condition caus ing the overload, said means comprisinga latch. normally biased to a released position and movable to alatching position to latch said contacts itiopen, an electromagnet formoving said latch to latching position when energized a predeterminedamount, a transformer the primary of which is connected in shuntrelation to said contacts and the secondary of which is connected inseries with said electromagnet, means for automatically connecting saidtransformer secondary and said electromagnet in shunt relation to theload when said lcontacts are automatically opened, the magnetic circuitof said electromagnet being such that its reluctance is changed only arelatively small amount by the movement of said latch to latchingposition so as to permit returnof said latch to released position whenthe current flowing through said electromagnet is decreased to a. valueonly slightly below the value required to cause said latch to be movedto latchingposition,` and adjusting means for varying the value ofcurrent required to cause said electromagnetto move said latch tolatchins position.

9. In a circuit breakerfrelatively movable contacts, actuating meansautomatically operablein response to predetermined conditions to opensaid l contacts and tothereafter reclose said contacts, a manualoperating handle' movable to cause 70 opening or closing of saidcontacts, an impedc ance connected at all times in shunt relation tosaid oontactarmeans operable upon automatic opening of said contacts forpreventing reclosing of said contacts as long as said predeterminedcondition exists, and means operable by opening movement o! the manualoperating handle for opening the circuit to interrupt the flow of cur-10. A circuit breaker for controlling a load circuit eomprisingrelatively movable contacts, actuating meansincluding an overcenterspring for opening and closing said contacts, an electro-responsiveelement operable to cause said spring to automatically open saidcontacts, in response to predetermined overload conditions and forcausing v'said spring to automatically reclose said contacts afterautomatic opening thereof, a manually operable handle operable to openand to close said contacts, an impedance connected in shunt to saidcontacts, and electromagnetic means operable upon .automatic opening ofsaid contacts to prevent reclosing of said contacts as long as theimpedance of Athe load circuit is below a predetermined value, andanadditional pair of contacts in the circuit opened by opening movement`of said manual operating handle for interrupting l0 the flow of currentin the circuit.

' OLIVER S. JENNINGS.

